In numerous interventions in a patient, instruments, especially catheters are introduced into the body. In addition to interventional radiological and electrophysiological procedures, these procedures also include neurological interventions or interventions in the abdominal area (at the liver or kidneys or gall bladder). As a matter of routine the position of the instrument introduced is monitored during such interventions by an x-ray system, that is by a monoplanar or biplanar system, which monitors the position of the instrument or the catheter which has been introduced. There is an increasing demand, as well as simply representing the instrument on a screen, to automatically determine its three-dimensional position and orientation. Then for example the three-dimensional position and the orientation of the instrument can be displayed on previously recorded three-dimensional image data, e.g. on a CT or a three-dimensional angiography. With electrophysiological methods too an automatic localization of objects is desirable for generating so-called electrophysiological maps.
Previously electroanatomical mapping systems (e.g. the CARTO system produced by Biosense Webster, Diamondbar, Calif., USA) have been used for three-dimensional real time localization of catheters during electrophysiological procedures. Special catheters with 6D position or orientation sensors are used in this product. The disadvantage of this is that only the special catheters can be localized and three-dimensionally visualized. The use of these catheters is also particularly associated with high costs.
In principle the three-dimensional localization of instruments using image data by detecting the instrument or a characteristic point in one or more images is also known. The 3D position can thus be determined using back projection from two x-ray images which are recorded from different directions for example.